# std::chrono::operator==,<=>(std::chrono::year_month_day)

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< cpp‎ | chrono‎ | year month day

Defined in header `<chrono>` |  |
constexpr bool operator==( const std::chrono::year_month_day& x, const std::chrono::year_month_day& y ) noexcept; | (1) | (since C++20)
constexpr std::strong_ordering operator<=>( const std::chrono::year_month_day& x, const std::chrono::year_month_day& y ) noexcept; | (2) | (since C++20)

Compares the two `year_month_day` values x and y. This is a lexicographical comparison: the `year()` is compared first, then `month()`, then `day()`.

The `<`, `<=`, `>`, `>=`, and `!=` operators are synthesized from operator<=> and operator== respectively.

### Return value

1) x.year() == y.year() && x.month() == y.month() && x.day() == y.day()
2) If x.year() <=> y.year != 0, x.year() <=> y.year; otherwise if x.month() <=> y.month() != 0, x.month() <=> y.month(); otherwise x.day() <=> y.day().

### Notes

If both x and y represent valid dates (x.ok() && y.ok() == true), the result of the lexicographical comparison is consistent with the calendar order.

### Example

Run this code

    #include <chrono>

    int main()
    {
        constexpr auto ymd1{std::chrono::day(13)/7/1337};
        constexpr auto ymd2{std::chrono::year(1337)/7/13};
        static_assert(ymd1 == ymd2);
        static_assert(ymd1 <= ymd2);
        static_assert(ymd1 >= ymd2);
        static_assert(ymd1 <=> ymd2 == 0);
    }

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